With the development of display technology, flat display devices, such as liquid crystal displays (LCDs), have been widely used in mobile phones due to their advantages of high picture quality, power saving, thin body, and wide application range. Various consumer electronic products, such as, televisions, personal digital assistants, digital cameras, notebook computers, and desktop computers have become mainstream in display devices.
Most of the liquid crystal display on the current market are backlight type liquid crystal display, which include a liquid crystal panel and a backlight module. The operation principle of the liquid crystal panel is to arrange liquid crystal molecules in two parallel glass substrates. There are many vertical and horizontal small wires in the middle of the two glass substrates. The liquid crystal molecules are controlled to change direction by being electrified, and the light of the backlight module is refracted so as to display the picture.
Since the liquid crystal panel itself does not emit light, the light source provided by the backlight module needs to display the image normally. Therefore, the backlight module is one of the key components of the liquid crystal display. The backlight module may include edge-type backlight modules and direct-type backlight modules according to the position of the light source. The direct-type backlight module is a backlight source, such as a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) light source disposed behind the liquid crystal panel. After the light is homogenized by the diffusion plate, a surface light source is provided to the LCD panel.
The direct type backlight module has the advantages of high performance, good optical stability, and the like. The conventional direct-type backlight module generally includes a back frame, a backlight provided in the back frame, an optical film disposed at a distance from the backlight source, and a diffusion plate disposed below the optical film. The optical film includes a device for improving the propagation of light from a backlight source, such as a prism sheet and a diffusion sheet. The diffusion sheet is different from a diffusion plate, which does not have a supporting function in a film form. The diffusion plate is used for light emitted from a light source. Diffusion provides support for the optical film at the same time, but the diffusion plate material is thick and the cost is high. If the diffusion plate is omitted, the optical film will collapse downwards, which will cause the quality of the backlight film to decrease.